Java中字符串大小写转换

public class TestCaculation { public static void main(String[] args) {           String str = args[0]; char[] ch = str.toCharArray();           for (int i=0;i<ch.length;i++){                ch[i] = (char)((ch[i]+(ch[i]/97)*59+32)%123);           }           System.out.println(new String(ch));      }}